There's truly no other book I've been able to find that goes in such depth with practical advice on how to make searches better. What's missing for a 5th star here is a bit more concrete, biased advice on what, in the authors experience, provides a decent base. I am also missing a methodology for improving search results, and a chapter on what it looks like to build a feedback loop to know whether you're improving search (or making it worse) based on conversion/click-through, etc.